An integrated circuit (“IC”) is a device (e.g., a semiconductor device) that includes many electronic components, such as transistors, resistors, diodes, etc. These components are often interconnected to form multiple circuit components, such as gates, cells, memory units, arithmetic units, controllers, decoders, etc. An IC includes multiple layers of wiring that interconnect its electronic and circuit components. Traditionally, IC's use preferred direction (“PD”) wiring models, which specify a preferred wiring direction for each of their wiring layers. In preferred direction wiring models, the preferred direction typically alternates between successive wiring layers.
One example of a PD wiring model is the PD Manhattan wiring model, which specifies alternating layers of preferred-direction horizontal and vertical wiring. An example of a newer PD wiring model is the PD diagonal wiring model, which specifies alternating layers of preferred-direction diagonal wiring. The PD diagonal wiring model can allow for shorter wiring distances than the PD Manhattan wiring model and can decrease the total wirelength needed to interconnect the electronic and circuit components of an IC.
Design engineers design IC's by transforming logical or circuit descriptions of the IC's components into geometric descriptions, called layouts. An IC layout comprises descriptions of each layer of the IC and typically include a variety of geometries such as (1) circuit modules (i.e., geometric representations of electronic or circuit IC components) with pins, and (2) interconnect lines (i.e., geometric representations of wiring) that connect the pins of the circuit modules. A net is typically defined as a collection of routable elements (e.g., pins) that need to be connected.
To create layouts, design engineers typically use electronic design automation (“EDA”) applications. These applications provide sets of computer-based tools for creating, editing, and analyzing IC design layouts. One EDA tool is a router that defines routes for interconnect lines that connect the routable elements (e.g., pins) of nets. In routing the routable elements of a net, a router may explore Manhattan routing directions, and more recently, diagonal routing directions on a layer of an IC to determine routes for connecting the routable elements. The various geometries of the IC layout are later physically created for an IC based on the descriptions of the various geometries in the IC layout.